C++11中多线程例子

C++11开始自带线程相关的操作库。这里举个例子，以并发编程最经典的例子，生产者消费者的例子来示例在C++11使用标准库提供的线程库来进行并发编程。

这里为了方便线程的使用，参考了android源码中对pthread的封装。

class Thread
{
public:
Thread()
: m_running(false)
{
}

virtual ~Thread()
{
if(m_running) {
m_running = false;
}
}

Thread(const Thread&) = delete;

Thread& operator=(const Thread&) = delete;

virtual bool threadRun() = 0;

bool start()
{
if (m_running) {

}
else {
m_running = true;
m_thread.reset(new std::thread(std::bind(&Thread::runImpl, this)));
m_thread->detach();
}
return m_running;
}

bool stop()
{
return m_running = false;
}

private:
void runImpl()
{
while (m_running && threadRun());
}

std::shared_ptr<std::thread> m_thread;
std::atomic_bool m_running;

};

对其进行了简单的封装，如果需要使用线程，继承

Thread

和实现

threadRun

这个接口，如果其返回true，那么线程将重复调用这个接口，如果其返回为false，那么线程将退出执行。

生产者

class ProduceThread : public Thread
{
public:
ProduceThread(std::queue<int> &q_, std::condition_variable& cv_, std::mutex& mutex_)
: Thread()
, m_q(q_)
, m_cv(cv_)
, m_mutex(mutex_)
{

}

bool threadRun()
{
sleep(rand() % 9);
std::unique_lock<std::mutex> _lock(m_mutex);
int _t = rand();
m_q.push(_t);
std::cout << "ProduceThread---" << _t << '\n';
m_cv.notify_one();
return true;
}

private:
std::queue<int>& m_q;
std::condition_variable& m_cv;
std::mutex& m_mutex;
};

消费者

class ConsumerThread : public Thread
{
public:
ConsumerThread(std::queue<int> &q_, std::condition_variable& cv_, std::mutex& mutex_)
: Thread()
, m_q(q_)
, m_cv(cv_)
, m_mutex(mutex_)
{

}

bool threadRun()
{
sleep(rand() % 4)
std::unique_lock<std::mutex> _lock(m_mutex);
if (m_q.empty()) {
m_cv.wait(_lock);
} else {
std::cout << "ConsumerThread---" << m_q.front() << '\n';
m_q.pop();
}
return true;

}

private:
std::queue<int>& m_q;
std::condition_variable& m_cv;
std::mutex& m_mutex;
};

这里使用了

condition_variable

来进行线程间的同步。

int main(int argc, char *argv[])
{
std::cout << "Hello World!" << std::endl;

std::condition_variable _cv;
std::mutex _mutex;
std::queue<int> _queue;

ProduceThread pt(_queue, _cv, _mutex);
ConsumerThread cp(_queue, _cv, _mutex);

cp.start();
pt.start();
sleep(20);

return 0;
}